diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
index c607f7606d..74b7856278 100644
--- a/hw/usb/dev-storage.c
+++ b/hw/usb/dev-storage.c
@@ -589,6 +589,13 @@ static const struct SCSIBusInfo usb_msd_scsi_info_bot = {
     .load_request = usb_msd_load_request,
 };
 
+static void usb_msd_unrealize_storage(USBDevice *dev, Error **errp)
+{
+    MSDState *s = USB_STORAGE_DEV(dev);
+
+    object_unref(OBJECT(&s->bus));
+}
+
 static void usb_msd_realize_storage(USBDevice *dev, Error **errp)
 {
     MSDState *s = USB_STORAGE_DEV(dev);
@@ -635,6 +642,13 @@ static void usb_msd_realize_storage(USBDevice *dev, Error **errp)
     s->scsi_dev = scsi_dev;
 }
 
+static void usb_msd_unrealize_bot(USBDevice *dev, Error **errp)
+{
+    MSDState *s = USB_STORAGE_DEV(dev);
+
+    object_unref(OBJECT(&s->bus));
+}
+
 static void usb_msd_realize_bot(USBDevice *dev, Error **errp)
 {
     MSDState *s = USB_STORAGE_DEV(dev);
@@ -755,6 +769,7 @@ static void usb_msd_class_initfn_storage(ObjectClass *klass, void *data)
     USBDeviceClass *uc = USB_DEVICE_CLASS(klass);
 
     uc->realize = usb_msd_realize_storage;
+    uc->unrealize = usb_msd_unrealize_storage;
     dc->props = msd_properties;
 }
 
@@ -817,6 +832,7 @@ static void usb_msd_class_initfn_bot(ObjectClass *klass, void *data)
     USBDeviceClass *uc = USB_DEVICE_CLASS(klass);
 
     uc->realize = usb_msd_realize_bot;
+    uc->unrealize = usb_msd_unrealize_bot;
     uc->attached_settable = true;
 }
 
diff --git a/hw/usb/dev-uas.c b/hw/usb/dev-uas.c
index 3b26655889..fffc424396 100644
--- a/hw/usb/dev-uas.c
+++ b/hw/usb/dev-uas.c
@@ -896,6 +896,8 @@ static void usb_uas_unrealize(USBDevice *dev, Error **errp)
     UASDevice *uas = USB_UAS(dev);
 
     qemu_bh_delete(uas->status_bh);
+
+    object_unref(OBJECT(&uas->bus));
 }
 
 static void usb_uas_realize(USBDevice *dev, Error **errp)